This invention relates generally to improved air/fuel apparatus and methods for gaseous fueled engines. More particularly, but not by way of limitation, this invention relates to an improved method and apparatus for supplying desired fuel/air mixtures to a gaseous fueled engine.
Carburetors are currently available for use with gaseous fueled engines. Available carburetors have proved to be generally satisfactory, but there are certain problems in such carburetors that reduce the efficiency of the engines with which they are used. For example, in one type of carburetor, as the flow therethrough increases, the flow area is increased in an attempt to maintain a constant pressure drop through the system. As the air flow increases, the gas flow is increased through the use of a valve which increases the opening area. The pressure drop across the carburetor is much larger than desirable; therefore, the power available is reduced and the efficiency of the engine is accordingly reduced.
In other types of conventional carburetors, there is a large pressure drop in the venturi throat at high air flows. The pressure drop is small at low flows with the variation being approximately directly related to square of the flow. The variation in this pressure, and particularly at the idle speeds and low air flow values, the carburetor is extremely difficult to control because of the effect of relatively small changes in either the air or the gas being supplied.
So far as is known, none of the conventional carburetors have throttles for the air and gas located upstream of the mixing; none provide for the conjoint control of the air and fuel throttle valves to maintain a constant air/fuel ratio at low and high flows, and none provide for the independent variation of the air/fuel ratio while providing conjoint control to maintain the desired air/fuel ratio.